Modelling river dune development

Since river dunes influence flow resistance, predictions of dune dimensions are required to make accurate water level predictions. A model approach to simulate developing river dunes is presented. The model is set-up to be appropriate, i.e. as simple as possible, but with sufficient accuracy for management purposes. Model results so far are promising. During floods, dunes develop on the river bed as a result of the interaction between flow and sediment transport. In the River Rhine, dunes can become 1-2 m in height and up to 50 m in length in a water depth of about 10 m. The dynamic behaviour of dunes is not yet completely understood. In our model, we include the processes that we think are most important for dune development, namely: the flow and sediment transport over dunes, and the formation of a wake behind the dunes.